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Intersection Safety Issue Briefs

Issue Brief 5

Traffic Signals

November 2009
FHWA-SA-10-005

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The introduction to this issue brief provides an overview of traffic signals (purpose, warrants for signal installation, advantages, disadvantages, and factors to consider) followed by an introduction to the contents of this issue brief (crash reduction factors, presentation of the crash reduction factors, and using the tables).

Purpose of Traffic Signals

Traffic signals are used to assign vehicular and pedestrian right-of-way. They are used to promote the orderly movement of vehicular and pedestrian traffic and to prevent excessive delay to traffic.

Traffic signals should not be installed unless one of the warrants specified by the Manual on Uniform Traffic Control Devices (MUTCD) has been satisfied. The satisfaction of a warrant is not in itself justification for a signal. A traffic engineering study must be conducted to determine whether the traffic signal should be installed. The installation of a traffic signal requires sound engineering judgment, and must balance the following, sometimes conflicting, goals:

Where Should a Signal Be Installed?

The MUTCD lists eight warrants for the placement of traffic signals. Readers are encouraged to review Part 4 of the MUTCD for more specific information regarding signal warrants. Access management considerations and the spacing of signals on arterial roadways are critical elements of system efficiency and operational safety. The basic question that must be answered is, "Will this intersection operate better with or without a traffic signal?"

Advantages of Signals

Traffic signals that are properly located and operated are likely to:

Disadvantages of Signals

Traffic control signals are often considered a panacea for all traffic problems at intersections. This belief has led to the installation of traffic control signals at many locations where they are not needed and where they may adversely affect the safety and efficiency of vehicular, bicycle, and pedestrian traffic.

Even when justified by traffic and roadway conditions, traffic control signals can be ill designed, ineffectively placed, improperly operated, or poorly maintained. Unjustified or improper traffic control signals can result in one or more of the following disadvantages:

As angle crashes tend to be more severe than rear-end crashes, traffic engineers are usually willing to trade off an increase in the number of rear-end crashes for a decrease in the number of angle crashes, but if an intersection does not have an angle-crash problem, the tradeoff does not apply, and the installation of traffic signals can actually cause a deterioration in the overall safety at the intersection.

Factors to Consider when Installing a Signal

A number of factors should be considered when planning to signalize an intersection. These factors include:

Signal Improvements That May Decrease Crashes

The following changes may decrease crashes:

Introduction to the Contents of this Issue Brief

This issue brief documents estimates of the crash reduction that might be expected if a specific countermeasure or group of countermeasures is implemented with respect to traffic signals. The crash reduction estimates are presented as crash reduction factors (CRFs).

Traffic engineers and other transportation professionals can use the information contained in this issue brief when asking the following types of question: Which countermeasures might be considered at the signalized intersection of Maple and Elm streets, an intersection that is experiencing a high number of crashes? What changes in the number of crashes are possible with the various countermeasures?

Crash Reduction Factors

A CRF is the percentage crash reduction that might be expected after implementing a given countermeasure. In some cases, the CRF is negative (i.e., the implementation of a countermeasure is expected to lead to a percentage increase in crashes).

One CRF estimate is provided for each countermeasure. Where multiple CRF estimates were available from the literature, selection criteria were used to choose which CRFs to include in the issue brief:

Where these criteria could not be met, a CRF may still be provided. In these cases, it is recognized that the reliability of the estimate of the CRF is low, but the estimate is the best available at this time. The CRFs in this issue brief may be periodically updated as new information becomes available.

The Desktop Reference for Countermeasures lists all of the CRFs included in this issue brief and adds many other CRFs available in the literature. A few CRFs found in the literature were not included in the Desktop Reference. These CRFs were considered to have too large a range or too large a standard error to be meaningful, or the original research did not provide sufficient detail for the CRF to be useful.

A CRF should be regarded as a generic estimate of the effectiveness of a countermeasure. The estimate is a useful guide, but it remains necessary to apply engineering judgment and to consider site-specific environmental, traffic volume, traffic mix, geometric, and operational conditions that will affect the safety impact of a countermeasure. The user must ensure that a countermeasure applies to the particular conditions being considered. The reader is also encouraged to obtain and review the original source documents for more detailed information and to search databases such as the National Transportation Library (http://ntlsearch.bts.gov) for information that becomes available after the publication of this issue brief.

Presentation of the Crash Reduction Factors

In the Table presented in this issue brief, the crash reduction estimates are provided in the following format:

CRF(standard error)REF

The CRF is the value selected from the literature.

The use of the color blue and the italicizing of words used in the text (except for words associated with a specific document) are associated with new information provided by the Highway Safety Manual, April 2009 draft, as listed in Reference 21 at the end of this issue brief.

The standard error is given where available. The standard error is the standard deviation of the error in the estimate of the CRF. The true value of the CRF is unknown. The standard error provides a measure of the accuracy of estimate of the true value of the CRF. The August 2008 edition of Issue Brief 5 used the phrase "relatively small" to indicate that a CRF is "relatively accurately known." Relatively small was not explicitly defined several years ago; however, its intention is congruent with the definition used in this edition of the Issue Brief: relatively small is defined as a CRF with a standard error ≤ 10. This is equivalent to the Highway Safety Manual AMFs (Accident Modification Factors) with standard errors of ≤ 0.10.

A "relatively large" standard error associated with a CRF is defined as >10 and indicates that the CRF is "not accurately known." The standard error may be used to estimate a confidence interval of the true value of the CRF. (An example of a confidence interval calculation is given below.) The REF is the reference number for the source information. As an example, the CRF for the countermeasure "provide protected left-turn phase for left-turn fatal/injury crashes" is:

17(4)21

The following points should be noted:

Using the Table

The CRFs for traffic signal-related crashes are presented in the Signalization Countermeasures Table that summarizes the available information.

Readers familiar with the previous editions of this issue brief will notice the following changes:

Table 1, Signalization Countermeasures is divided into three sections: signal operations countermeasures; signal hardware countermeasures; and combination signal and other countermeasures. This table is also found in Issue Brief No. 8, which includes a more comprehensive toolbox of countermeasures for consideration at intersections.

The following points should be noted:

Legend

CRF(standard error)REF

CRF is a crash reduction factor, which is an estimate of the percentage reduction that might be expected after implementing a given countermeasure. A number in bold indicates a rigorous study methodology and a small standard error (≤10) in the value of the CRF. Standard error, where available, is the standard deviation of the error in the estimate of the CRF.

REF is the reference number for the source information.

Additional crash types identified in the Other Crashes column:

a: Head-on

b: Run-off-road

c: Overturn

d: Night

e: Day

f: Multiple-vehicle

g: Fixed-object

h: Older-driver

i: Younger-driver

j: Right-turn

k: Pedestrian

l: Emergency vehicle

Table 1. Signalization Countermeasures
Countermeasure Crash Severity Control Area Type Configuration All Crashes Left-Turn Crashes Rt-Angle Crashes Rear-end Crashes Sideswipe Crashes Other Crashes Major/ Minor Daily Traffic Volume (veh/day)
Signal Operations Countermeasures
Add all-red clearance interval (from 0 to 1 second) All Signal Urban empty cell empty cell empty cell empty cell empty cell empty cell empty cell empty cell
Add exclusive pedestrian phasing All Signal empty cell empty cell empty cell empty cell 0(44)14 empty cell empty cell k (34)7 empty cell
Convert exclusive leading protected to exclusive lagging protected All Signal empty cell empty cell -15(19)6 -49(54)6 empty cell empty cell empty cell empty cell empty cell
Convert permissive or permissive/ protected to protected only left-turn phasing All empty cell empty cell empty cell empty cell 9920 empty cell empty cell empty cell empty cell empty cell
Convert permissive to permissive/ protected left-turn phasingAll All empty cell empty cell empty cell empty cell 1620 empty cell empty cell empty cell empty cell empty cell
Convert protected left-turn phase to protected/ permissive All Signal empty cell empty cell -20(17)15 -65(71)6 empty cell 4(22)6 empty cell empty cell empty cell
Convert protected left-turn phase to protected/ permissive Fatal/ Injury Signal empty cell empty cell -10(25)15 empty cell empty cell empty cell empty cell empty cell empty cell
Convert permissive to protected All Signal Urban 4-leg or 3-leg 6(10)21 99(1)21
Convert permissive to protected/ permissive or permissive/ protected phasing Injury Signal Urban 4-leg 16(2)21 3,000- 77,000/ 10-45,500
Convert permissive to protected/ permissive or permissive/ protected phasing All Signal Urban 4-leg 121
Convert permissive to protected left-turn phase on multiple approaches All Signal on 1 approach 621
Convert permissive to protected left-turn phase on multiple approaches All Signal on 2 approaches 1121
Convert permissive to protected left-turn phase on multiple approaches All Signal on 3 approaches 1721
Convert permissive to protected left-turn phase on multiple approaches All Signal on 4 approaches 2221
Convert permissive to protected/ permissive or permissive/ protected left turn phase on multiple approaches All Signal empty cell on 1 approach 121 empty cell empty cell empty cell empty cell empty cell empty cell
Convert permissive to protected/ permissive or permissive/ protected left turn phase on multiple approaches All Signal empty cell on 2 approaches 221 empty cell empty cell empty cell empty cell empty cell empty cell
Convert permissive to protected/ permissive or permissive/ protected left turn phase on multiple approaches All Signal empty cell on 3 approaches 321 empty cell empty cell empty cell empty cell empty cell empty cell
Convert permissive to protected/ permissive or permissive/ protected left turn phase on multiple approaches All Signal empty cell on 4 approaches 421 empty cell empty cell empty cell empty cell empty cell empty cell
Convert protected/ permissive left-turn phase to permissive/ protected All Signal empty cell empty cell -13(19)8 33(22)8 empty cell empty cell empty cell empty cell empty cell
Improve signal timing [to intervals specified by the ITE Determining Vehicle Change Intervals: A Proposed Recommended Practice (1985)] All Signal empty cell 4-leg 8(9)15 empty cell 4(18)15 -12(16)15 empty cell h 4212 empty cell
Improve signal timing [to intervals specified by the ITE Determining Vehicle Change Intervals: A Proposed Recommended Practice (1985)] All Signal All empty cell empty cell empty cell empty cell empty cell empty cell f 55 empty cell
Improve signal timing [to intervals specified by the ITE Determining Vehicle Change Intervals: A Proposed Recommended Practice (1985)] All Signal empty cell empty cell empty cell 754 empty cell empty cell empty cell empty cell empty cell
Improve signal timing [to intervals specified by the ITE Determining Vehicle Change Intervals: A Proposed Recommended Practice (1985)] Fatal/ Injury Signal empty cell empty cell empty cell 554 304 empty cell empty cell a 754 empty cell
Improve signal timing [to intervals specified by the ITE Determining Vehicle Change Intervals: A Proposed Recommended Practice (1985)] Fatal/ Injury Signal empty cell empty cell empty cell empty cell empty cell empty cell empty cell b 624 empty cell
Improve signal timing [to intervals specified by the ITE Determining Vehicle Change Intervals: A Proposed Recommended Practice (1985)] Fatal/ Injury Signal empty cell 4-leg 12(9)15 empty cell -6(22)15 -8(17)15 empty cell empty cell empty cell
Improve signal timing [to intervals specified by the ITE Determining Vehicle Change Intervals: A Proposed Recommended Practice (1985)] Fatal/ Injury Signal All empty cell empty cell empty cell empty cell empty cell empty cell f 95 empty cell
Improve signal timing [to intervals specified by the ITE Determining Vehicle Change Intervals: A Proposed Recommended Practice (1985)] Fatal/ Injury empty cell empty cell empty cell empty cell empty cell empty cell empty cell empty cell k 3715 empty cell
Improve signal timing [to intervals specified by the ITE Determining Vehicle Change Intervals: A Proposed Recommended Practice (1985)] PDO empty cell empty cell empty cell empty cell 634 464 174 empty cell b 284 empty cell
Increase yellow change interval All Signal empty cell empty cell 154 empty cell 304 empty cell empty cell empty cell empty cell
Install emergency vehicle pre-emption systems All empty cell empty cell empty cell empty cell empty cell empty cell empty cell empty cell l 7016 empty cell
Modify signal phasing (implement a leading pedestrian interval) All Signal empty cell empty cell empty cell empty cell empty cell empty cell empty cell k 57 empty cell
Provide Advanced Dilemma Zone Detection for rural high-speed approaches Fatal/ Injury Signal Rural 4-leg (1 app) 3919 empty cell empty cell empty cell empty cell empty cell empty cell
Provide protected left-turn phase Fatal/ Injury Signal Urban empty cell empty cell 17(4)21 25(2)21 empty cell empty cell empty cell empty cell
Provide protected left-turn phase All Signal empty cell empty cell 304 414 544 274 empty cell c 274 <5,000/ lane (Total)
Provide protected left-turn phase All Signal empty cell empty cell 364 464 564 354 empty cell c 354 <5,000/ lane (Total)
Provide protected left-turn phase All Signal empty cell empty cell 274 484 634 314 empty cell c 314 empty cell
Provide protected/ permissive left-turn phase (leading green arrow) Fatal/ Injury Signal Urban empty cell empty cell 17(2)9 25(2)9 empty cell empty cell empty cell empty cell
Provide signal coordination All Signal empty cell empty cell empty cell empty cell 327 empty cell empty cell empty cell empty cell
Provide split phases All Signal empty cell empty cell 257 empty cell empty cell empty cell empty cell empty cell empty cell
Remove flash mode (late night/ early morning) All Signal empty cell empty cell 297 empty cell 75(19)7 empty cell empty cell empty cell empty cell
Replace existing WALK/ DON'T WALK signals with pedestrian countdown signal heads All Signal Urban empty cell empty cell empty cell empty cell empty cell empty cell k 2510 empty cell
Signal Hardware Countermeasures
Add 3-inch yellow retroreflective sheeting to signal backplates All Signal Urban empty cell 15(51)17 empty cell empty cell empty cell empty cell empty cell empty cell
Add additional signal and upgrade to 12-inch lenses All Signal empty cell 4-leg empty cell empty cell empty cell empty cell empty cell h 3112 empty cell
Add additional signal and upgrade to 12-inch lenses All Signal empty cell 4-leg empty cell empty cell empty cell empty cell empty cell h 1712 empty cell
Add signal (additional primary head) All Signal Urban 4-leg 282 empty cell 352 282 empty cell empty cell empty cell
Add signal (additional primary head) Fatal/ Injury Signal Urban 4-leg 172 empty cell empty cell empty cell empty cell empty cell empty cell
Add signal (additional primary head) PDO Signal Urban 4-leg 312 empty cell empty cell empty cell empty cell empty cell empty cell
Convert signal from pedestal-mounted to mast arm All Signal empty cell empty cell 4916 1216 7416 4116 empty cell empty cell empty cell
Convert signal from pedestal-mounted to mast arm Fatal/ Injury Signal empty cell empty cell 4416 empty cell empty cell empty cell empty cell empty cell empty cell
Convert signal from pedestal-mounted to mast arm PDO Signal empty cell empty cell 5116 empty cell empty cell empty cell empty cell empty cell empty cell
Improve visibility of signal heads (increase signal lens size, install new backboards, add reflective tape to existing backboards, and/or install additional signal heads) All Signal Urban empty cell 718 empty cell empty cell empty cell empty cell d 618 empty cell
Improve visibility of signal heads (increase signal lens size, install new backboards, add reflective tape to existing backboards, and/or install additional signal heads) All Signal Urban empty cell empty cell empty cell empty cell empty cell empty cell e 618 empty cell
Improve visibility of signal heads (increase signal lens size, install new backboards, add reflective tape to existing backboards, and/or install additional signal heads) Fatal/ Injury Signal Urban empty cell 318 empty cell empty cell empty cell empty cell empty cell empty cell
Improve visibility of signal heads (increase signal lens size, install new backboards, add reflective tape to existing backboards, and/or install additional signal heads) PDO Signal Urban empty cell 918 empty cell empty cell empty cell empty cell empty cell empty cell
Improve visibility of signal heads (install two red displays in each head) All Signal empty cell empty cell 97 empty cell 367 empty cell empty cell empty cell empty cell
Install larger signal lenses (12 inch) All Signal empty cell empty cell 117 empty cell 4614 empty cell empty cell empty cell empty cell
Install larger signal lenses (12 inch) All Signal Urban empty cell 2417 empty cell empty cell empty cell empty cell empty cell empty cell
Install larger signal lenses (12 inch) Fatal/ Injury Signal Urban empty cell 1617 empty cell empty cell empty cell empty cell empty cell empty cell
Install signal backplates only All Signal empty cell empty cell 137 empty cell 507 empty cell empty cell empty cell empty cell
Install signal backplates (or visors) All Signal empty cell empty cell empty cell empty cell 204 empty cell empty cell empty cell empty cell
Install signals All No Signal empty cell empty cell 337 3813 empty cell empty cell empty cell j 5013 empty cell
Install signals All No Signal empty cell empty cell 384 empty cell 749 229 empty cell c 224 <5,000/ lane (Total)
Install signals All No Signal empty cell empty cell 204 empty cell 439 209 empty cell c 204 >5,000/ lane (Total)
Install signals All No Signal Rural empty cell 1513 empty cell empty cell empty cell empty cell empty cell empty cell
Install signals All Stop Urban 4-leg 5(9)21 67(6)21 -143(40)21
Install signals All Stop Rural 3-leg or 4-leg 44(3)21 60(6)21 77(2)21 -58(20)21 3,300-30,000/ 100-10,300
Install signals Fatal No Signal empty cell empty cell 3813 empty cell empty cell empty cell empty cell empty cell empty cell
Install signals Fatal/ Injury Stop Urban 3-leg 14(32)11 empty cell 34(45)11 -50(51)11 empty cell empty cell 11,750-42,000/ 900-4000
Install signals Fatal/ Injury Stop Urban 4-leg 23(22)11 empty cell 67(20)11 -38(39)11 empty cell empty cell 12,650- 22,400/ 2,400- 3,625
Install signals PDO No Signal empty cell empty cell -1513 empty cell empty cell empty cell empty cell empty cell empty cell
Install signals (temporary) Fatal/ Injury No Signal empty cell empty cell empty cell empty cell 394 empty cell 504 empty cell empty cell
Install signals (temporary) PDO No Signal empty cell empty cell empty cell 114 734 empty cell empty cell a 834 empty cell
Install signals (to have one over each approach lane) All empty cell All empty cell empty cell empty cell 463 empty cell empty cell empty cell empty cell
Remove unwarranted signals All Signal Urban empty cell 24(9)21 empty cell 24(10)21 29(20)21 empty cell d 305 empty cell
Remove unwarranted signals All Signal Urban empty cell empty cell empty cell empty cell empty cell empty cell e 225 empty cell
Remove unwarranted signals All Signal Urban empty cell empty cell empty cell empty cell empty cell empty cell g 315 empty cell
Remove unwarranted signals Fatal/ Injury Signal Urban empty cell 535 empty cell empty cell empty cell empty cell empty cell empty cell
Remove unwarranted signals PDO Signal Urban empty cell 245 empty cell empty cell empty cell empty cell empty cell empty cell
Remove unwarranted signals Pedestrian Signal Urban One-lane one-way streets excluding major arterials 18(30)21 empty cell empty cell empty cell empty cell empty cell empty cell
Replace signal lenses with optical lenses All Signal empty cell empty cell 177 104 104 104 empty cell a 204 empty cell
Combination Signal and Other Countermeasures
Install left turn lane and add turn phase All Signal empty cell empty cell 587 empty cell empty cell empty cell empty cell empty cell empty cell
Install signals and add channelization Fatal/ Injury No Signal empty cell empty cell empty cell empty cell 674 empty cell 544 b 354 empty cell
Install signals and add channelization PDO No Signal empty cell empty cell empty cell 244 634 empty cell empty cell a 274 empty cell
Note: Any CRF with a reference of 21 is added to this version of the Intersection Safety Issue Brief 5.


References

1. Bahar, G., Parkhill, M., Hauer, E., Council, F., Persaud, B., Zegeer, C., Elvik, R., Smiley, A., and Scott, B. "Prepare Parts I and II of a Highway Safety Manual: Knowledge Base for Part II." Unpublished material from NCHRP Project 17-27, (2007)

2. Felipe, E., Mitic, D., and Zein, S. R., "Safety Benefits of Additional Primary Signal Heads." Vancouver, B.C., Insurance Corporation of British Columbia; G.D. Hamilton Associates, (1998)

3. FHWA and Institute of Transportation Engineers, "Making Intersections Safer: A Toolbox of Engineering Countermeasures to Reduce Red-Light Running." FHWA/TX-03/4027-2, Texas Transportation Institute, (2002)

4. Gan, A., Shen, J., and Rodriguez, A., "Update of Florida Crash Reduction Factors and Countermeasures to Improve the Development of District Safety Improvement Projects." Florida Department of Transportation, (2005)

5. Harkey, D., Srinivasan, R., Zegeer, C., Persaud, B., Lyon, C., Eccles, K., Council, F. M., and McGee, H., "Crash Reduction Factors for Traffic Engineering and Intelligent Transportation System (ITS) Improvements: State of Knowledge Report." Research Results Digest, Vol. 299, Transportation Research Board of the National Academies, (2005)

6. Hauer, E., "Left Turn Protection, Safety, Delay and Guidelines: A Literature Review." www.roadsafetyresearch.com, (2004)

7. Institute of Transportation Engineers, "Toolbox of Countermeasures and Their Potential Effectiveness to Make Intersections Safer." Briefing Sheet 8, ITE, FHWA, (2004)

8. Lee, J. C., Wortman, R. H., Hook, D. J., and Poppe, M. J., "Comparative Analysis of Leading and Lagging Left Turns." Phoenix, Arizona Department of Transportation, (1991)

9. Lyon, C, Haq, A., Persaud, B. N., and Kodama, S. T. , "Development of Safety Performance Functions for Signalized Intersections in a Large Urban Area and Application to Evaluation of Left Turn Priority Treatment." 2005 TRB 84th Annual Meeting: Compendium of Papers CD-ROM, Vol. TRB#05-2192,Washington, D.C., (2005)

10. Markowitz, F., Sciortino, S., Fleck, J.L., and Yee, B.M., "Pedestrian Countdown Signals: Experience with an Extensive Pilot Installation." Institute of Transportation Engineers Journal, January 2006, pp. 43-48. Updated by Memorandum, Olea, R., "Collision changes 2002-2004 and countdown signals," (February 7th, 2006)

11. McGee, H., Taori, S., and Persaud, B. N., "NCHRP Report 491: Crash Experience Warrant for Traffic Signals." Washington, D.C., Transportation Research Board, National Research Council, (2003)

12. Morena, D. A., Wainwright, W. S., and Ranck, F., "Older Drivers at a Crossroads." Public Roads, Vol. 70, No. 4, Washington, D.C., FHWA, (2007) pp. 6-15

13. Pernia, J.C., Lu, J.J., Weng, M.X., Xie, X., and Yu, Z., "Development of Models to Quantify the Impacts of Signalization on Intersection Crashes." Florida Department of Transportation, (2002)

14. Polanis, S. F., "Low-Cost Safety Improvements. Chapter 27, The Traffic Safety Toolbox: A Primer on Traffic Safety," Washington, D.C., Institution of Transportation Engineers (1999) pp. 265-272

15. Retting, R. A., Chapline, J. F., and Williams, A. F., "Changes in Crash Risk Following Re-timing of Traffic Signal Change Intervals." Accident Analysis and Prevention, Vol. 34, No. 2, Oxford, N.Y., Pergamon Press, (2002) pp. 215-220

16. Rodegerdts, L. A., Nevers, B., and Robinson, B., "Signalized Intersections: Informational Guide." FHWA-HRT-04-091, (2004)

17. Sayed, T., Leur, P. , and Pump, J., "Safety Impact of Increased Traffic Signal Backboards Conspicuity." 2005 TRB 84th Annual Meeting: Compendium of Papers CD-ROM, Vol. TRB#05-16, Washington, D.C., (2005)

18. Sayed, T., El Esawey, M., and Pump, J., "Evaluating the Safety Impacts of Improving Signal Visibility at Urban Signalized Intersections." 2007 TRB 86th Annual Meeting: Compendium of Papers CD-ROM, Vol. TRB#07-135, Washington, D.C., (2007)

19. Zimmerman, K. and Bonneson, J., "In-Service Evaluation of the Detection-Control System for Isolated High-Speed Intersections." 2006 TRB 85th Annual Meeting: Compendium of Papers CD-ROM, Vol. TRB#06-1252, Washington, D.C., (2006)

20. Harkey, D., Srinivasan, R., Baek, J., Council, F. M., Eccles, K., Lefler, N., Gross, F., Persaud, B., Lyon, C., Hauer, E., and Bonneson, J. A., "Crash Reduction Factors for Traffic Engineering and ITS Improvements," NCHRP Report No. 617, (2008)

21. Highway Safety Manual 1st Edition. AASHTO. April 2009 Draft.

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